Access the Magnifier by:Triple-clicking the Home button for iPhone 8/8 Plus and earlier or
Triple-clicking the side button on iPhone X

Consider other Accessibility Settings

While enabling the Magnifier, consider other accessibility settings that may be useful. As Apple says, “The world’s most personal device was designed for every person. So a person who’s blind can take group selfies. A person who’s deaf can call Mom from overseas. And a person who can’t move from the neck down can send text messages to friends.” You can add closed captioning to media (where available), turn on an LED flash for alerts, modify the keyboard, or pair your iPhone with your hearing device.